Vibro Acoustic Analysis of 630 kVA Transformer Core

Abstract

Nowadays the problem of noise in urban area has gained a great attention. The cities have been growing up, putting the citizens under increasing acoustical discomfort not only at their work environment but also inside their own homes. While traffic is the main source of noise in the cities, other sources such as civil constructions and electrical energy substations often produce more noise in their vicinity than nearby traffic. The main source of noise from the electrical energy substation located inside the urban area is the transformer. The principal sound sources in transformer are: 1. Core sound caused by magnetostriction effects and inter-laminar forces. 2. Load sound caused by electromagnetic forces in the windings, tank walls and magnetic shunts due to leakage flux associated with current. 3. Cooling equipment sound caused by fans (aerodynamic and motor/bearing sound) and pumps (cavitations and motor/ bearing sound). From the study of literature, it has been found out that major contribution of transformer noise is magnetostriction. In the present work, 630 kVA transformer noise due to magnetostriction has been studied. The main objective of this work is to develop a numerical procedure for predicting magnetostriction noise from the transformer core. The vibro-acoustic studies have been done to predict the noise of transformer core using electromagnetic, static, modal, harmonic and acoustic analysis. The results have been validated with experimental results. In addition to this, free vibration behavior of core, frame and core-frame assembly has been studied by varying different design parameters like width and thickness for two different core and frame designs. This work has been done at the Analytical Center, Global R&D, Crompton Greaves Ltd., Mumbai.